Task: Send feedback from Google Sheets to Mattermost

n8n workflow:
{"nodes":[{"name":"Cron","type":"n8n-nodes-base.cron","position":[450,300],"parameters":{"triggerTimes":{"item":[{"mode":"custom","cronExpression":"0 0 17 28 9 *"}]}},"typeVersion":1},{"name":"Google Sheets","type":"n8n-nodes-base.googleSheets","position":[650,300],"parameters":{"range":"Sessions!A:D","options":{},"sheetId":"1nlnsTQKGgQZN-Rtd07K9bn0ROm0aFBC2O4kzM2YaTBI","authentication":"oAuth2"},"credentials":{"googleSheetsOAuth2Api":"n8ndocsburner-googlesheets"},"typeVersion":1},{"name":"Mattermost","type":"n8n-nodes-base.mattermost","position":[850,300],"parameters":{"message":"= Hey @channel, we hope you had a great time at **{{$node[\"Google Sheets\"].json[\"Session\"]}}**.\nLet us know how we did by sharing your feedback with us on the link below!","channelId":"={{$node[\"Google Sheets\"].json[\"Mattermost Channel ID\"]}}","attachments":[{"title":"=Feedback Form - {{$node[\"Google Sheets\"].json[\"Session\"]}}","title_link":"={{$node[\"Google Sheets\"].json[\"Feedback Form Link\"]}}"}],"otherOptions":{}},"credentials":{"mattermostApi":"mm_failedmachine"},"typeVersion":1}],"connections":{"Cron":{"main":[[{"node":"Google Sheets","type":"main","index":0}]]},"Google Sheets":{"main":[[{"node":"Mattermost","type":"main","index":0}]]}}}