You will find older versions here
https://sourceforge.net/projects/lms-plugins-philippe44/files/
BUT manual installs are slightly different.
First uninstall what is there through the plugins page. Untick, apply. reboot.
Then download the version of interest from the link above.
I hope I remember this bit correctly.
Unzip on PC and copy to the Plugins folder which is located somewhere like - /usr/local/slimserver/Plugins -
IMPORTANT - NOT the Plugins folder inside /usr/local/slimserver/Cache/ - the former is for manually installed Plugins only the latter for ones installed through the web tool
Restart LMS