Having trouble installing OpenVPN Access Server

I've followed every step in the https://www.linode.com/docs/guides/install-openvpn-access-server-on-linux/ guide.

I'm stuck at step 4, which asks to install the binary. I use the Ubuntu terminal code but I encounter an error. This is what happens when I execute the line of code inside the terminal:

snow@snowvpn:~$ sudo dpkg -i openvpn-as-*.deb
(Reading database … 77446 files and directories currently installed.)
Preparing to unpack openvpn-as-2.5.2-Debian9.amd_64.deb …
Upgrade detected (debian)…
Unpacking openvpn-as (2.5.2-Debian9) over (2.5.2-Debian9) …
Setting up openvpn-as (2.5.2-Debian9) …
Backing up configuration and DB files to /usr/local/openvpn_as/etc/backup prior to update.
ERROR: Could not read active profile name: profile/key _INTERNAL/run_api.active_profile not found in sqlite:////usr/local/openvpn_as/etc/db/config.db: util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,<string>:1,sagent/sagent_entry:38,db/confdb_admin:354,util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,util/error:61,util/error:44
ERROR: Could not read active profile name: profile/key _INTERNAL/run_api.active_profile not found in sqlite:////usr/local/openvpn_as/etc/db/config.db: util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,<string>:1,sagent/sagent_entry:38,db/confdb_admin:354,util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,util/error:61,util/error:44
ERROR: Could not read active profile name: profile/key _INTERNAL/run_api.active_profile not found in sqlite:////usr/local/openvpn_as/etc/db/config.db: util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,<string>:1,sagent/sagent_entry:38,db/confdb_admin:354,util/options:79,db/confdb_admin:280,db/confdb:531,db/confdb:523,util/error:61,util/error:44</string></string></string>

Do you know what is going on? Thanks