Hi, Give me your site URL and also screenshot of your issue please

If I may.... " how to have the login menu displayed on the off-canvas menu"

You can publish any module in mobile menu, just create/add new module and choose "offcanvas" position for it.

About changing +/- to "arrows" it request CSS override, the only method as I know. Try this:

.offcanvas-menu .offcanvas-inner .sp-module ul > li.menu-parent > a > .menu-toggler::after, 
.offcanvas-menu .offcanvas-inner .sp-module ul > li.menu-parent > .menu-separator > .menu-toggler::after
{ content: "\f078";}


.offcanvas-menu .offcanvas-inner .sp-module ul > li.menu-parent.menu-parent-open > a > .menu-toggler::after
{content: "\f077";}

Thanks Paul, My meaning is how to publish the login module in the bottom of the Off-canvas menu, and get it displayed as on Joomshaper page with a arrow to develop the menu "options" instead of having the basic full joomla login module.

I guess you have to find extra module for this purpose. Sorry, for me it looks like customization question, beyond support.