@ljutica, only Storeman ≥ 0.3.0 works properly on SailfishOS 4.4.0. The principal “landing page” (with all necessary information and further web-links) for Storeman & Storeman Installer is Storeman Installer | OpenRepos.net — Community Repository System.
Background: mentaljam / osetr ceased working on Storeman in October 2021 and asked publicly for others to maintain Storeman & Storeman Installer in March 2022.
I volunteered to organise the infrastructure for managing Storeman & Storeman Installer as a team and thus became the maintainer of Storeman. Unfortunately there are currently no other contributors, hence I simply try to keep Storeman & Storeman Installer working on new SailfishOS releases and further development of Storeman is still on the hold.
@ohnonot, if one already has the SailfishOS-Chum GUI app installed, there is no need to use the Storeman Installer: Storeman can be directly installed from the SailfishOS:Chum repository.