I know the question has more than one year, but was the first thing that popped up on google with "phpmyadmin ec2". Here is a better way to do things.
Knowing that you have yum, the best way to act is to install it by yum, being a RHEL distribution you can "activate" the EPEL repository ( Extra Packages for Enterprise Linux), where you can find phpmyadmin and some other stuff.
Here you can see a package list for the EPEL repo.
There is 2 way to use EPEL, one is to activate it permanently, editing the file
/etc/yum.repos.d/epel.repo and where it says
enabled=0 we change it to
enabled=1, now you can
sudo yum install phpmyadmin.
The easy way is to activate it just to install the packages you want, like mongodb or phpmyadmin.
sudo yum --enablerepo=epel install phpmyadmin
and it should work.
EDIT (comment by @eric-brotto):
It also should be noted that this comes with the advantage of uninstalling via
(sudo) yum erase phpmyadmin
Eric Brotto Jun 8 at 16:22