Hello, a noob here '-'

I'm having a Wordops installation issue

when I executed wget -qO wo wops.cc && sudo bash wo
it gave few errors but (supposedly) completed

`
root@Wdelivery:_# wget -qO wo wordops.io/install && sudo bash wo

Welcome to WordOps install script v3.9.6.1

Updating apt-get repository info
W: The repository 'http://security.ubuntu.com/ubuntu stretch-security Release' does not have a Release file.
W: The repository 'http://mirrors.digitalocean.com/ubuntu stretch Release' does not have a Release file.
W: The repository 'http://mirrors.digitalocean.com/ubuntu stretch-updates Release' does not have a Release file.
W: The repository 'http://mirrors.digitalocean.com/ubuntu stretch-backports Release' does not have a Release file.
E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/stretch-security/main/source/Sources 404 Not Found [IP: 91.189.91.26 80]
E: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/stretch/main/source/Sources 404 Not Found [IP: 104.24.116.209 80]
E: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/stretch-updates/multiverse/source/Sources 404 Not Found [IP: 104.24.116.209 80]
E: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/stretch-backports/main/source/Sources 404 Not Found [IP: 104.24.116.209 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
Installing wo dependencies
Installing WordOps
Applying Kernel tweaks
Installing acme.sh
Running post-install steps
wo: line 765: wo: command not found
WordOps (wo) installed successfully
For autocompletion, run the following command:
source /etc/bash_completion.d/wo_auto.rc
`

I'm getting similar errors when executing the apt-get update.
It is worth mentioning that I am using digital ocean servers.
what could be the problem?