`siamplain.bst` not found when template in texmf

With the suggested installation of the Poster template in the Wiki, the placement of the repository (locally) in the texmf-tree does not find siamplain.bst.

Suggested Path of repository: ${HOME}/texmf/tex/latex/mpi2015-postertemplate

Run:

cd example && latexmk -pdf example

Issue: Bibtex complains,

This is BibTeX, Version 0.99d (TeX Live 2022/dev/Debian)
The top-level auxiliary file: poster.aux
I couldn't open style file siamplain.bst
---line 19 of file poster.aux
 : \bibstyle{siamplain
 :                    }

This could be fixed by placing/linking the bst file in the path BibTeX expects, i.e. ${HOME}/texmf/bibtex/bst/siamplain.bst, but either this should be specifically mentioned or rather avoided by informing BibTeX programmatically through some other means.