This is makeindex, version 2.15 [TeX Live 2021] (kpathsea + Thai support).
Scanning style file /Users/christianmartin/Documents/LatexProjekte/VorlageTeX/abschlussarbeit.ist.............................done (29 attributes redefined, 0 ignored).
Scanning input file /Users/christianmartin/Documents/LatexProjekte/VorlageTeX/abschlussarbeit.acn....done (148 entries accepted, 0 rejected).
Sorting entries....done (1190 comparisons).
Generating output file /Users/christianmartin/Documents/LatexProjekte/VorlageTeX/abschlussarbeit.acr....done (119 lines written, 0 warnings).
Output written in /Users/christianmartin/Documents/LatexProjekte/VorlageTeX/abschlussarbeit.acr.
Transcript written in /Users/christianmartin/Documents/LatexProjekte/VorlageTeX/abschlussarbeit.alg.