Weddings
Will older guests manage with it?
The short answer
In most cases, yes, as long as the explanation is short and the link opens straight in the browser with no app to install.
For guests who are less fond of technology, the most important thing is not to overload them. Do not talk about systems, do not ask for too many steps, and do not hide the action behind a long block of text.
You can also help through a family member, the reception table, or a member of staff. At family events it works well when one person knows how to explain things calmly.