Ok there are so many reasons why this isn’t something to post here.
Not the least of which is Ardour7 is not even released at this point, and hasn’t even really entered beta testing. There is still lots of development happening on it and NOONE should be using it for production work at this point. The only reason to use any version of Ardour7 at this point is if you are actively involved with the development, in which case you wouldn’t be posting this here but rather be involved in IRC.
Starting with Ardour 7, there will only be support for the following OS:
macOS 10.11 (or later)
GNU/Linux systems with libstdc++.so.5 (or later)
Windows 7 (or later)
The reason for this is rather technical. We would like to use some modern (really 10 year old) C++11 features. Some older OS do not directly support this.