Please ensure MAT is set up correctly by following this guide
From the menu select File-> New-> Project from Existing Sources and select the mat directory from the base of the mat git repository and be sure to select maven as the external model
After it is imported, do a Build -> Rebuild Project to ensure it is all set up correctly
From the menu select Run-> New-> Edit Configurations
Click on the + in the upper left-hand corner. Select Tomcat server -> Local
You should see a dialog like this
change URL to http://localhost:8080/mat/
Click on the Fix button and select the war or the exploded directory. The exploded directory is faster for development.
in the VM options text box, add the following and edit for your configuration.
-Xmx1G
-DVSAC_DRC_URL=https://vsac.nlm.nih.gov/vsac
-DSERVER_TICKET_URL=https://vsac.nlm.nih.gov/vsac/ws/Ticket
-DSERVER_SINGLE_VALUESET_URL=https://vsac.nlm.nih.gov/vsac/ws/RetrieveValueSet?
-DSERVER_MULTIPLE_VALUESET_URL_NEW=https://vsac.nlm.nih.gov/vsac/svs/RetrieveMultipleValueSets?
-DSERVICE_URL=http://umlsks.nlm.nih.gov
-DENVIRONMENT=DEV
-Dlog4j.ignoreTCL=true
-DPROFILE_SERVICE=https://vsac.nlm.nih.gov/vsac/profiles
-DVERSION_SERVICE=https://vsac.nlm.nih.gov/vsac/oid/
-D2FA_AUTH_CLASS=mat.server.twofactorauth.DefaultOTPValidatorForUser
-D2FA_AUTH_CLASS1=mat.server.twofactorauth.DefaultOTPValidatorForUser
-DBONNIE_RESPONSE_TYPE=code
-DBONNIE_REDIRECT_URI=https//yourredirectURI.com
-DBONNIE_CLIENT_ID=1234567890
-DBONNIE_CLIENT_SECRET=1234567890
-DBONNIE_URI=https://bonnieURL.org
-DALGORITHM=EncyptionAlgorithm
-DPASSWORDKEY=PasswordKey
-Dlog4j.configuration=PathToLog4jPropertiesFile
Now from the intellij menu, you should be able to run or debug the MAT application.