What you need is to do:

1. open your Ancesty a_*.csv file in Charting Companion 7+ to have it generate a a GEDcom file of your matches. If you already have a RootsMagic file with your matches included in a custom DNA fact that has their Guid in the Details fields, you can skip this step.
2. Open the Gedcom in RootsMagic 10.
3. Add yourself and direct ancestors into this new database. Include your full Ancestry DNA ID into the Details of the custom Fact DNA Kit inside of RootsMagic 10 (This looks like ABCD-01234-5678-9000). BACKUP!! this databse, and make a copy to play with at first.
4. Run the python script, and enter the location of your DNAGedcom database, and the RootsMagic 10 database you just created. Ensure ethnicities.json is in the same directory as DNAG2RM.py.
5. Run Database tools within RootsMagic 10, and run SmartMerge. You'll want to start finding duplicates after this.
6. Check your ICWs as well.