You can get samples from a lot of places.
I'll list some sources of samples you can use:
You can also rip samples from other modules.
A very popular source of XI instruments is KIArchive. This one is highly recommended, since all the instruments are already set up for you!
The most popular source of modules is The Mod Archive.
ModLand is also very popular, and has a lot of modules!
There's plenty other ones out there.
The Mod Archive forums and the Tracker Music Discord server are my go-tos!
3.3. WORKING WITH THE PATTERN EDITOR
6. GOOD SOURCES