I'd need more information to help work out what is causing that error.
Sticky Element doesn't print an error message like that so perhaps something else is going wrong with PHP or WordPress is having trouble activating the plugin for another reason.
Feel free to post more info!
No reply so marking as resolved.
Had the same issue. Line 116 in the PHP code, register_mysettings is a little generic and caused a conflict with another plugin that must have used the same thing.
Changed it to register_mystickysettings on line 113 and 116, activates just fine.
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