I want to sell Motion Graphics Templates files on Adobe Stock / I applied, but got no response.

A couple of possibilities:

1. Your samples are not what they are looking for.  No invitation was made.

2. Stock is being more selective about who they invite, they prefer to work with trusted partners & agencies.

3. Motion Graphics Templates are not a big enough seller.

Was there an invitation to apply? According to Design Template Requirements for Adobe Stock Contributors

"At the moment, we’re sourcing design templates from a small group of artists and agencies — we’re not accepting submissions from individual contributors at this time. Over time, we may be expanding them to include a broader group of contributors — we’ll keep you up to date in our Contributor newsletters and notifications. "

Given that, I would not expect any reply if I asked to be a template contributor.

Give a short reminder and ask them if they have a timeline for considering your candidacy. I'm sure they answer the request, if positive or negative.