How To Create A Flat Rate Promo Code?

We'd like to create a flat rate shipping price promo code for orders that are $99 or more. It doesn't seem to be possible in the promotions options. Is this even possible or will it require customization?

I am afraid, additional code modification is required if you do not want to specify flat rate for each shipping method manually. Feel free to contact us

It requires customization. We can implement it approximately for USD 300 ( https://simtechdev.com/helpdesk )

We are also at your service