Also in the instruction from your link I do you understand the purpose of the "-m 0755" text included in the command shown below?
sudo install -m 0755 -o root -g root -t /usr/local/bin bitcoin-0.18.0/bin/*
is used to configure permission of the installed application.
0755 (in order) means :
0 : AFAIK it's indication whether it's directory or file, CMIIW
7 : Full permission (read, write, execute) for current user (root)
5 : Read and execute permission for group
5 : Read and execute permission for other user & group
Shouldn't I be using a DEB file to install this application? This is one aspect that has me confused. Lastly, can you share any knowledge you may have regarding dependency files Bitcoin Core needs to install correctly? Or does Ubuntu 18 already have all dependent files Bitcoin Core needs? Thanks for your help with this matter.
.deb is just one way to install application on linux