On page 115 of the "AppleShare Pro Administrator's Guide" you will find the AppleShare Pro Specifications appendix.
Here is the contents of that page regarding the AppleShare Pro File Server:
| Maximum connected users | 200 |
| Maximum number of open files | 5,000 (may require adding RAM) |
| Maximum number of volumes | 50 |
| Maximum number of shared items | 50 |
| Maximum number of users in a user/group file | 2,000 (Recommended) |
| Maximum number of groups in a user/group file | 2,000 (Recommended) |
| Maximum number of group memberships per user | 42 |
| Maximum number of simultaneous launches | 200 |
Note: The maximum number of users in a user/group file and maximum number of groups in a user/group file in the manual is stated at 2,000. However, AppleShare Pro is based on AppleShare 4.0 code and the maximum number of users in a user/group file and maximum number of groups in a user/group file in the "AppleShare Administrator's Guide, Version 4" is stated as 8,192 (2,000 recommended).