[horde] installation challenges

[o1bigtenor]

Greetings

A longer term linux user but a noob at system administration.

Trying to install horde groupwebmail (IIRC the name!) on Debian stretch
with php7.1.8, postgresql9.6, apache2.4.25.

Php was an incredible challenge to get it to install but I think I was able
to complete things (there was an install PEAR environment:
/usr/local.lib/php/ and 8 following lines after many hundreds of lines of
'stuff').

I have attempted to setup and configure and try a few things on Postgresql
in that past so that part was somewhat easier.

Apache2 and I are still not really friends but I think I was able to
achieve an install there as well (got to the Apache page on the browser).

The closest install directives were for Debian Jessie and php5 so things
were not always straightforward.

At present I am at a stage where it seems like ZEND  is the issue. I come
to that conclusion because there are a number of statements (with different
numbers) saying:

/tmp/pear/temp/pam/pam.c:xxx:xx: error: macro "ZVAL_STRING" passed 3
arguments, but takes just 2

(means that there is 2 real pieces of whatever noted and the 3rd is
actually a 0 but I really have no clue as to do with that!)

I found this page

https://github.com/beberlei/beberlei.de/blob/8ed2b9394b641bcf3b7d2bc1038792afbf29dce2/drafts/porting_extension_to_php7.rst

which is where I get the idea that the ZVAL_STRING is part of zend.

I am not sure as to what to do to change the outcome though.

I tried downloading the source code package from Debian for Linux-PAM-1.1.8
and installed it (it ended without throwing a bunch of errors).

Still was unable to affect an installation.

Any ideas as to what to add?
(Please with some guidance.)

TIA

Dee