There is actually a known issue with AutoCAD for Mac licenses issued from the Education Community.
Please refer to the this page for a workaround for your AutoCAD for Mac Activation issue. Specifically:
If you are using AutoCAD for Mac, you can activate the software by:
1) choosing to install the software in trial mode 2) when launching the program in trial mode (once installed) you will be faced with run / continue in “trial mode” or “activate” - select the activation option 3) follow the process (enter Serial Number and Product Key) to circumvent the previous issue and allow for a proper activation
Please feel free to let us know if you have any additional questions or inquiries.