This is not a propagation issue, when the DNS servers of DigitalOcean are queried directly they also say your hostname does not exist.
It’s also not a Discourse issue - please contact DigitalOcean support about this.
; <<>> DiG 9.16.1-Ubuntu <<>> www.ludoa.ba @ns1.digitalocean.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4644
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;www.ludoa.ba. IN A
;; AUTHORITY SECTION:
ludoa.ba. 1800 IN SOA ns1.digitalocean.com. hostmaster.ludoa.ba. 1669066654 10800 3600 604800 1800