Before you can save your work, you need to activate Isadora 3 or 4 with a valid license.
You can find out more about the various Isadora license types from this article, and you can purchase a license on our Isadora Get It page.
Upon purchasing a license, your license activation information will be sent to you via email and you'll be able to follow these instructions to activate Isadora.
After activating your license you will be able to save your work.
Note that Subscription, Rental, and Isadora 4 Perpetual Licenses will work for both Isadora 3 and 4.