The Registered Domain in your case is
gate.ru. And yes, it means you can only get 50 certificates per week for new subdomains (excluding renewals).
If you are creating some sort of hosting platform using your
*.wp.gate.ru domain, then you may apply for a rate limit exemption based on that domain and/or your ACME account.
You can find the link to apply for an exemption on this page: https://letsencrypt.org/docs/rate-limits/#a-id-overrides-a-overrides . It usually takes a few weeks to get a response.
You can also just try using a single wildcard certificate for
*.wp.gate.ru, and using that to protect all of your domains.