First, be sure to choose the DSP as "Google Display & Video 360" in NEXD Campaign Manager before publishing the creative.
Step 1 : Create the creative
When receiving NEXD Campaign Manager tag after publishing the campaign. (Article NEXD Campaign Manager Distribution Tags) You have to create a new Creative in Google Display & Video 360 as a Third Party Creative.
Step 2 : Insert the data and tag
After opening the third party banner option window. Fill in the name, set the size, require HTML5 and copy the NEXD Campaign Manager Distribution Tag to the Tag field.
Step 3 : If the tag is inserted, please check the preview so the creative is working
The layout should look something like this.
Step 4: Save it and you have your NEXD creative in Display & Video 360.
For full walkthrough:
Hopefully it was as easy as it should be. :)