Cannot get Xerte LTI via Tsugi Working

I have an XAMPP install of Xertes (3.10.5).
I want to enable "Publish project through Tsugi as an LTI1 tool" on it.
I referenced these instructions:

How to install TSUGI
Xerte specific instructions for installing Tsugi and using LTI
httpz://xot.xerte.org.uk/play.php?template_id=88#page1

Which apply to Xerte v3.11

There is a link in these instructions:

old instruction to install tsugi
httpz://xot.xerte.org.uk/play.php?template_id=88#

However this link just takes you back to the v3.11 instructions.

Therefore for my v3.10.5 install,
I had to infer things as best I could.

I obtained tsugi at:

httpz://github.com/tsugiproject/tsugi

And installed it in the path of my Xerte installation at:

C:\xampp\htdocs\xertetoolkits\tsugi

This appeared to be correct,
As for a Xerte Project this option is now available:

Publish project through Tsugi as an LTI1 tool

And a key and secret can be generated for a project.
Additionally 2 LTI URLs (1.1 and 1.3) are available for a project.

However when I attempt to use these LTI URLs in our Blackboard,
With the generated key and secret,
It results in an error page with a message such as this:

Oops, something went wrong.
OAuth validation fail key=Art_Project_2 delta=1 error=Invalid signature ours= uoPdz7J4RE6gEULkfdOuXskutey= yours=1gn3awK2j3Hc37FtrnBMJCKjumL=

What do I need to do to resolve this error?

NOTE:
As a new user I am unable to put real URLs in my post.
Therefore I used HTTPZ instead.

If the XAMPP installation is running on your personal PC, this is really a bad idea in production. Normally there are all kinds of routers and firewalls between your PC and the blackboard installation.

Anyway, I fixed the link to the old documentation, so, please verify that everything is installed correctly.

The error indicates there is a mismatch between the URL given in the configuration end the URL actully sent buh the software. This can be caused by routerss, proxies, reverse proxies between the blackboard installation and your Xerte install. The blackboard machine should be able to ceonnect to the xerte installation using the smae URL as you use to open Xerte.