This can be accomplished using the IF() function within a configuration. Question: are you creating the Project using a template manually using the Add Project from the Navigation bar on left side bar or are you using a custom intake form?

If you are using a custom intake form, you can add the functionality to the intake form configuration to link the appropriate group based on region selected. If manually created, a separate workflow rule that will replicate this action on Project creation will resolve the same. This will require using the New Item action and selecting the Group Project Link with two variables, group and entity. Entity is easy, it references the new Project or CurrentObject(). The Group would use the IF() function and look similar to this…

IF($Region=UK,’UK-Group’,’AMER-Group’)

Note: If you have more than two options, you can use a nested IF and include more options or the Case() function. Here is a link to the functions article for more details on each function available.

https://success.planview.com/Planview_AdaptiveWork/Working_in_AdaptiveWork/Reports%2C_Functions%2C_and_Relation_Tables/AdaptiveWork_Functions

Region is project level custom field, however I have written a custom action at task level. There is a flag at task level. If that flag is true then this custom action will be displayed to pm to send the project to approver user group. I gave the if condition like you suggested but it did not go to that user group however went to other default user group.

In that case, did you use $ParentProject.C_Region as the region reference? This is required so it looks at the Region on the task’s parent project object, not task itself.