How does storage capacity work? If one uses Standalone to save documents the storage capacity is the computer´s capacity? And when one creates a group library, what is the storage capacity?
You have unlimited personal storage capacity with Zotero. You're only limited by the size of your computer's hard drive.
The only limitation comes with server space and attachment syncing. If you want to upload your full-text PDFs to Zotero's servers, you have 300MB for free, with the option of buying more server space. This is a very handy function for personal use, but is not necessary.
For groups, your cloud storage space is determined by the group owner's storage quota. It might be wise to assign group ownership to a person who doesn't use much of their own personal space so that your group will have up to 300MB of free space to use.
Of course, buying more server space from Zotero is pretty affordable too, so it might be worth considering for bigger projects.
Upgrade Storage
The only limitation comes with server space and attachment syncing. If you want to upload your full-text PDFs to Zotero's servers, you have 300MB for free, with the option of buying more server space. This is a very handy function for personal use, but is not necessary.
For groups, your cloud storage space is determined by the group owner's storage quota. It might be wise to assign group ownership to a person who doesn't use much of their own personal space so that your group will have up to 300MB of free space to use.
Of course, buying more server space from Zotero is pretty affordable too, so it might be worth considering for bigger projects.