Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
The Product Schema is already added on your products.
Rank Math takes the schema data from your product pages automatically and turns it into Schema-ready content. Likewise, the aggregateRating and review fields are taken from your actual product reviews that your buyers/customers leave on your products.

If you don’t have any reviews yet, that is going to show up as an error in the schema testing tool. That’s because Google will actually look for those fields.
Please acquire some reviews and ratings to get rid of the aggregateRating and review warnings.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.