To begin, log in to your Zenloop account and navigate to the data or reports section. Use the export function to download your data in a CSV or Excel format. Make sure the file includes all necessary fields that you need to import into the Oracle Database.

Open the exported file using a spreadsheet application like Microsoft Excel or Google Sheets. Clean the data by ensuring that there are no empty fields, duplicates, or inconsistencies. Save the cleaned data in CSV format, as this is widely supported for importing into databases.

Access your Oracle Database using an SQL client like SQL*Plus or SQL Developer. Use the following SQL command to create a table structure that matches the data fields in your CSV file:
```sql
CREATE TABLE zenloop_data (
field1 VARCHAR2(255),
field2 NUMBER,
field3 DATE,
...
);
```
Adjust the field names and data types to match your CSV data structure.

Use a secure method to transfer your CSV file to the server where your Oracle Database resides. You can use SCP (Secure Copy Protocol) or SFTP (SSH File Transfer Protocol) for this purpose. Ensure you have the necessary permissions and network access to upload the file to the server.

Once the CSV file is on the Oracle server, use the Oracle SQL*Loader utility to import the data into the database table. Create a control file `load_data.ctl` with the following content:
```plaintext
LOAD DATA
INFILE 'your_data.csv'
INTO TABLE zenloop_data
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
(field1, field2, field3, ...)
```
Execute the SQL*Loader command:
```bash
sqlldr userid=your_username/your_password@your_database control=load_data.ctl
```

After loading the data, verify the import by running a SELECT query:
```sql
SELECT * FROM zenloop_data;
```
Check for data integrity and ensure that the records in the table match your original data set. Look out for any errors or missing data points.

Finally, optimize the table by creating indexes on frequently queried columns to improve performance:
```sql
CREATE INDEX idx_field1 ON zenloop_data(field1);
```
Ensure data security by setting appropriate user permissions and roles in Oracle to restrict access to only authorized personnel.

By following these steps, you successfully move data from Zenloop to an Oracle Database without relying on third-party connectors or integrations, ensuring a smooth and secure data migration process.