You can set maximum number of nights in two ways on OTA Sync platform:
To add/edit compact value do this:
Go to Settings > Prices & Restrictions > Restricions
Add New Restriction of Type: Compact and adjust Max Stay
Edit the Pricing Plan you want to apply with this Restriction and down in Restrictions select restriction plan you just created.
To add/edit daily value do this:
Again first create restriction plan but now Type: Daily (or just use our default restriction plan that is automatically created)
Edit the Daily restriction plan and add default Maximum Stay
Now if you want to edit maximum stay for only specific days to be different than default values you should go to Calendar > Prices and Restrictions
Then choose date range you wish to update. Tab Restrictions. Restriction Plan to update. Expand Room Type Settings and enter maximum stay you want. Submit.