Blocked IP address when setting up Infobip email subdomain

I’ve created a email subdomain within Infobip for a domain hosted by cloudflare.
The A record generated by Infobip has expected value 104.21.34.6.

When the client set up this A record cloudflare gave the following error.

Can we get the steps how to get a new IP address assigned for this?
What more information do I need to provide?

Full error text below - removing links as I’m not allowed to post more than 4 links.

Query terms are ambiguous. The query is assumed to be:

“n 104.21.34.6”

Use “?” to get help.

NetRange: 104.16.0.0 - 104.31.255.255
CIDR: 104.16.0.0/12
NetName: CLOUDFLARENET
NetHandle: NET-104-16-0-0-1
Parent: NET104 (NET-104-0-0-0-0)
NetType: Direct Allocation
OriginAS: AS13335
Organization: Cloudflare, Inc. (CLOUD14)
RegDate: 2014-03-28
Updated: 2021-05-26
Comment: All Cloudflare abuse reporting can be done via
Ref:

Hello,

If an A record in your Cloudflare DNS app refers to a Cloudflare IP address, change it to your origin web server IP address. Contact your hosting provider if you need assistance acquiring the origin IP address.