Thank you for your response, @ctgraham. Excuse me the delay in my response, I have had to resolve an important problem occurs in the website where I works: someone hacked us (it isn’t the first time). At the bottom of this message I explain briefly the cause, because it is related with OJS 
I have used git before, I am not an expert, but I want to improve my knowledge and my experience with git, so I am not worry to use it 
What you have said about disable Strict Standards remember me that I can’t use PHP 7.0 with my OJS installation, because it shows me a white page in which I can’t do anything.
I finally install again OJS via git, but it install OJS 3.0.1 and not 3.0.2. I don’t understand why, but I have doubts. I am trying to make a git rebase, using ojs-3_0_2-0 as the new version and ojs-3_0_1-0 as origin, but it didn’t works. If if execute git rebase --onto ojs-3_0_2-0 ojs-3_0_1-0, I get the next error:
fatal: Needed a single revision
invalid upstream ojs-3_0_1-0
What could it be happening? If nobody knows how could be solved it, I will try to install again OJS 3.0.2 via git.
I am going to open a new message about the security issue that I am going to comment, but I want to speak about it briefly in this message because it is very important to consider. I have confirmed with my hosting service that someone upload a script inside a phtml file and it was auto-executed, infecting all my sites (not only the OJS installation, even a Wordpress installation and an empty subdomain). I have read “Security issue: Hacking via submission in OJS 2.4.8” and, reading exactly the first message of Palmpilic, we have suffered in the same way: hacker registration that upload an phtml to files dir and then generate html, php and txt files similar. I will post another topic for that, but I would like that you consider this because it happens to me with OJS 3.0.1.
Thanks in advance. I hope we could solved this soon.
Regards