\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[osf,p]{libertinus}
\usepackage{microtype}
\usepackage[pdfusetitle,hidelinks]{hyperref}
\usepackage[english]{babel}
\usepackage{lipsum}
\SetLipsumParListEnd{\par}

\usepackage[series={A,B,C,D,E},noend,noeledsec,nofamiliar,noledgroup]{reledmac}

\newcounter{mynotelevel}%A counter to dump the note level
\renewcommand{\themynotelevel}{\Alph{mynotelevel}}% The counter is seen as a letter
\AtEveryPstart{%
  \addtocounter{mynotelevel}{1}%Step counter
  \ifnumequal{\value{mynotelevel}}{6}{%No more than 5
    \setcounter{mynotelevel}{1}%
  }{}%
  \global\letcs{\mynote}{\themynotelevel footnote}%Change the mynote
  \seriesatend{\themynotelevel}%And place current series at the end
}
\begin{document}
\date{}
\title{One series per \textbackslash pstart with reledmac}
\author{}
\maketitle
\begin{abstract}
This file provides examples of features that allow one series of notes by \verb+\pstart+…\verb+pend+.

We suppose there is no more than five \verb+\pstart+…\verb+pend+ by page.

Instead of using \verb+\Afootnote+, \verb+\Bfootnote+ etc., we use \verb+\mynote+, which we set to \verb+\Afootnote+ at the first \verb+pstart+, \verb+\Bfootnote+ at the second \verb+\pstart+, \verb+\Cfootnote+ at the third, \verb+\Dfootnote+ at the fourth, \verb+\Efootnote+ at the fifth. And we restart at \verb+\Afootnote+ at the sixth \verb+\pstart+.

To do this, we increment the counter \verb+mynotelevel+ at every \verb+pstart+ and reset it to~1 when it becomes equal to~6.

We use \verb+\seriesatend+ to ensure that a \verb+pstart+ series between two pages will be printed on the first page at the end of the series, but on the second page at the beginning of the series.
\end{abstract}

    \beginnumbering

    \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel first}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[1]
    \pend

    \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

    \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

        \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend
        \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]\edtext{on otherpage}{\mynote{on otherpage}}
    \pend

        \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

        \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend


            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend
            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend

            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend


            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend


            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend


            \pstart
    \edtext{\themynotelevel Here}{\mynote{First footnote in \themynotelevel}} is the
    \edtext{\themynotelevel second}{\mynote{Second footnote in \themynotelevel.}} paragraph:
    \lipsum[2]
    \pend
    \endnumbering

\end{document}
