Fully Friendly URL - Products URL Masking

[BilalArif]

Hello,

I want to rewrite URL, Selected Option is: Fully Friendly Rewrite

When I hit the URL like this https://mydomain.com/whmcs/order-Linux-Basic this should be referring to a product which is added in WHMCS. Few updates before, this was working fine but I think new rewrite rules and condition is causing issue and it is showing: 404 Not found Error

Such lines are added after default code - Please let me know what to change to get this URL. Thank you

RewriteRule ^order-Linux-Basic$ cart.php?a=add&pid=2

### BEGIN - WHMCS managed rules - DO NOT EDIT BETWEEN WHMCS MARKERS ###
<IfModule mod_rewrite.c>
RewriteEngine on

# RewriteBase is set to "/" so rules do not need updating if the
# installation directory is relocated.  It is imperative that
# there is also a RewriteCond rule later that can effectively get
# the actual value by comparison against the request URI.
# 
# If there are _any_ other RewriteBase directives in this file,
# the last entry will take precedence!
RewriteBase /



# Redirect directories to an address with slash
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+[^/])$  $1/ [R]


# Send all remaining (routable paths) through index.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# Determine and use the actual base
RewriteCond $0#%{REQUEST_URI} ([^#]*)#(.*)\1$
RewriteRule ^.*$ %2index.php [QSA,L]


</IfModule>
### END - WHMCS managed rules - DO NOT EDIT BETWEEN WHMCS MARKERS ###