Hi,
Sorry for the issue. Easy to correct, but Donate button must be hidden in Mobile view  to have space for [=] menu icon.
As we teach in Helix Ultimate guide, in Template Options > Custom Code > Custom CSS 
Copy & paste those lines
@media screen and (max-width: 840px) {
#sp-menu .sp-module {display: none;}
#offcanvas-toggler {line-height: 75px; height: 75px;font-size: 20px;}
.burger-icon {width: 25px;cursor: pointer;}
.burger-icon > span {display: block; height: 3px; background-color: #000; margin: 4px 0;}
#sp-header #offcanvas-toggler {display: flex; align-items: center;}
}
    Just do it, and Save settings. You can also use (new) custom.css file.
    Remember to check if Menu module was published in "offcanvas" position as well, with chosen Menu.