new install to 3.x but missing 'Extensions' module?

Hi, Just upgraded from OC 2.x to 3.x, the install seemed to go okay. Looks like I now have version 3.0.2.0.

However, when I log into my admin, I see some error lines at top relating to line 141 and currency.php. I searched about this and found an extension that supposedly fixes this problem, here - https://www.opencart.com/index.php?rout ... d=8&page=4

My problem is that I can't even seem to install this extension because in my Admin section, I seem to be completely missing the 'Extensions' section where I believe I would go to install extensions. This Extensions section is just missing completely for me.

Any idea how to either:

1) install the mentioned extension above without using the Admin 'Extensions' section?
2) fix the admin section and restore the 'Extensions' section

Appreciate any help.

Thank you.

Here's a screenshot of what it looks like in my Admin. Error message up top.

And I believe there should be a section for 'Extensions' on the left where it has 'Catalog', 'Design', 'Sales' and the other sections but it's missing?

In admin dashboard go to the system/users/user groups edit administrator permissions. select all access permissions and modify permissions.

Cheers

This worked perfect, thank you!