TeamTime is compatible with all editions of SharePoint 2010, 2013, 2016, 2019 and SharePoint Server Subscription Edition
Unfortunately TeamTime does not support SharePoint Online / Office 365, due to the restrictiveness of the environment.
No.
TeamTime is licensed per server; this means it has no user restrictions and no user licenses.
You can have an unlimited number of TeamTime sites, each containing as many users as you like; see below for guideline amounts of users per site.
Each TeamTime site should contain around 10-50 users, with a maximum of 100. Data can be consolidated from several sites for Reporting and Analysis by using the Overview Site, and there is no limit to the number of TeamTime sites you can have. Keeping the individual sites quite small has these benefits:
TeamTime now offers extensibility lists, to allow you to directly integrate with the data. Please see: Extensibility
Due to the recommended sizes of each TeamTime site (Please see "How many users can I have in each TeamTime site?" above), we don't offer the facility to split users within a site. Instead we'd recommend splitting the users into different sites for each team.
Each TeamTime site should contain around 10-50 users, with a maximum of 100. Data can be consolidated from several sites for Reporting and Analysis by using the Overview Site, and there is no limit to the number of TeamTime sites you can have. Keeping the individual sites quite small has these benefits:
Custom Columns added to your site are automatically displayed on the timesheet. Please see the guide for more information: Custom Column Guide
TeamTime allows for three user types: User, Manager, and Administrator. SharePoint's default permission groups don't separate out Managers, but a new group can be added with the Approve permission to cover this type of user.
More information can be found here: User Permissions