Materials, layers and other attributes can be imported via the Attribute Manager.
Libraries (objects) just need to be loaded in the Library Manager.
If you have an old template, just open it in 25 (or what ever version you want to work in).
Then just update to that version library, you may also need to load the migration libraries - depending what objects you have in your template.
Look at the migration section in the reference manual.
One of the forum moderators. Versions 6.5 to 25 Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10 Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10