Question about general scope of Terra app support?

Hi All, 

I am new to Terra and I have been assigned to work on comparing some various workflow running  web apps. We use an in-house and open source tool, for example, to analyze BAMs here. (https://majiq.biociphers.org) On some other platforms I have been able to specify a docker repository in order to run this custom tool as part of the workflow. Is this supported on Terra? 

Also, I was trying to make an example test workflow with a new WDL on the editor following these instructions: https://support.terra.bio/hc/en-us/articles/360031366091-Create-and-or-edit-a-new-workflow , but after I click 'create new method' and fill in the details, and click 'upload', I get:

"Error: Authorization exception for user <my email address> attempting to exercise permission Create on entity test1.test1.-1.