.ssh dir should be 700 or drwx——

Generate keys:

$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/urlogin/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/urlogin/.ssh/id_rsa.
Your public key has been saved in /home/urlogin/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:XXX...---...XXX urlogin@urhost.tdn
The key's randomart image is:
+---[RSA 2048]----+
....
+----[SHA256]-----+
$ ls -lh
total 8.0K
-rw------- 1 urlogin urgroup 1.8K Aug 24 08:41 id_rsa
-rw-r--r-- 1 urlogin urgroup  412 Aug 24 08:41 id_rsa.pub

Copy id_rsa.pub to ~/.ssh and add it to authorized_keys or authorized_keys2:

cat .id_rsa.pub >> authorized_keys

Ensure authorized_keys is rw only for user:

chmod 600 authorized_keys

If message appears:

sign_and_send_pubkey: signing failed: agent refused operation

There is a problem with ssh-agent:

$ eval `ssh-agent -s` 
$ ssh-add