Can't Download Signatures as CSV

Hello,

I left a post on another thread about this, but I didn’t get any answers. I’m still unable to download the CSV of my petition signatures:
https://www.bringbackbritishrail.org/content/wp-admin/admin.php?page=dk_speakup_signatures

I read this post here:
https://www.ads-software.com/support/topic/plugin-speakup-email-petitions-unable-to-download-as-csv

On your advice, I have switched on DEBUG mode and tried again. I am pasting the error I get below, in case you are able to help.

I will also try disabling the other plugins before downloading to see if this helps.

Please let me know if you have any ideas.

very best wishes,

Ellie

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Deprecated: Assigning the return value of new by reference is deprecated in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/plugins/audio-player/audio-player.php on line 903

Notice: Undefined index: HTTPS in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/plugins/audio-player/audio-player.php on line 127

Notice: Undefined index: SERVER_PORT_SECURE in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/plugins/audio-player/audio-player.php on line 127

Notice: load_plugin_textdomain was called with an argument that is deprecated since version 2.7 with no alternative available. in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-includes/functions.php on line 3197

Notice: Undefined variable: type in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/themes/intercity102/functions.php on line 10

Notice: Undefined variable: core_update in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/themes/intercity102/functions.php on line 10

Notice: Undefined variable: result in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-content/themes/intercity102/functions.php on line 10

Notice: has_cap was called with an argument that is deprecated since version 2.0! Usage of user levels by plugins and themes is deprecated. Use roles and capabilities instead. in /home/bringbackbritishrail/bringbackbritishrail.org/content/wp-includes/functions.php on line 3195

https://www.ads-software.com/plugins/speakup-email-petitions/