NextScripts

Please go to plugin Settings Page -> Filters and include only “post” in the post types section. Alternatively you can exclude unnecessary post types.

Пункт 6 инструкции:

6. Важно!

Напишите e-mail на: api-support@ok.ru о том, что у вас есть вебсайт и вы бы хотели размещать новости или посты вашего сайта (или блога) в вашей ok.ru группе. А также напишите в письме, что вы создали application с ID xxxxxxxxxxxxxx(Application ID из шага 4 выше) и вы бы хотели получить для него следующие права: GROUP_CONTENT, PHOTO_CONTENT, VALUABLE_ACCESS.

Судя по ошибке

User must grant an access to permission ‘GROUP_CONTENT‘”,”error_data”:”group_content

вы либо не послушались инструкции и не попросили GROUP_CONTENT, либо вам его не дали по каким-то причинам. В любом случае, пишите в саппорт снова и просите GROUP_CONTENT. (а так же PHOTO_CONTENT и VALUABLE_ACCESS, если вы не просили и их)

please check error_log file for the details of that 500 error

That basically means that your custom post type is not following the standard WordPress way of creating posts.

Our plugin posts to all configured social networks at the time post goes live. Technically speaking our plugin is hooked to the event of changing post status from whatever to “Published”. This event is triggered when you hit “Publish” button, when you post on your site from email, when you publish post from your iOS/Android Device, when external plugin correctly published new post, and when scheduled post becomes live.

When any kind of event of changing post status from whatever to “Published” happens plugin writes this to the log:

[2018-01-04 13:25:09] [User ID:1] – [*** ID: 542, Type: post]- Status Changed: draft_to_publish. Autopost requested.

If you don’t have that in the log, your custom post type does not do that event.

The word “account” here does not mean a Facebook account. It means an account added to SNAP plugin.

It works like this (in Pro):
You click green “Add new Account” button, you chose Facebook, you set it up and connect to your Facebook account. At the last step you chose profile, page or group.
You click green “Add new Account” button again, you chose Facebook, you set it up and connect to the same or different Facebook account. At the last step you choose a different profile, page or group.

Now you got two accounts where SNAP will autopost.

If you need to setup 20 groups from the same Facebook account, there is a “Duplicate” button. You just need to click it 20 times and then select a different group for each account copy.

Free version can post to only one profile, page or group.

The most common reason for this is the amount of memory allowed for PHP on your server. Please check and make sure it’s not 32M or less. You need at least 64M, but if you have other plugins 128M or even 256M is recommended.

If you memory is fine, please check error_log file for the details of that 500 error.

Are you getting any errors?
Please check your Log/History page and let me know what do you have there.

goo.gl is not always stable.